Question: Marvin lives in Stormwind City and works as an engineer in the city of Ironforge. In the morning, he has $3$ transportation options (teleport, ride a dragon, or walk) to work, and in the evening he has the same $3$ choices for his trip home. If Marvin randomly chooses his method of travel in the morning and in the evening, what is the probability that he teleports at least once per day?
Answer: $\text{Probability} = \dfrac{\text{Favorable outcomes}}{\text{Total possible outcomes}}$ There are $3$ possible choices for each trip, so there are $3\times3=9$ total ways he can get to work and back. If Marvin chooses randomly, each outcome is equally likely. The green rows show the outcomes where Marvin teleports at least once. There are $5$ favorable outcomes. Morning Evening ${\text{Teleport}}$ ${\text{Teleport}}$ ${\text{Teleport}}$ ${\text{Dragon}}$ ${\text{Teleport}}$ ${\text{Walk}}$ ${\text{Dragon}}$ ${\text{Teleport}}$ Dragon Dragon Dragon Walk ${\text{Walk}}$ ${\text{Teleport}}$ Walk Dragon Walk Walk The probability that Marvin will teleport at least once is $5$ out of $9$, or $\dfrac59$.